This study investigates renal functional reserve in elderly.

The prevalence of CKD in elder is high as age has been a variable in eGFR equation. eGFR by calculation always declines in parallel with age. The assumption that a persistent over 3 months of eGFR less than 60 mL/min/1.73m2 define CKD with risk of progression and need refer to nephrologist may not necessary true in aging population. We study renal functional reserve in elderly population who risk of CKD progression and ESRD is the highest prevalence in human life cycle and explore whether renal functional reserve can be used as ad additional marker of CKD progression in elderly.

Inclusion Criteria:

• Patient age > 60 years at screening
• Patient willing to participate in the study and can provide inform consent
• Patient have residual kidney function ≤ 90 ml/min/1.73m2 by CKD-EPI equation

Exclusion Criteria:

• Patient active smoking
• Patient have Charlson comorbidity index > .....
• Patient active cancer
• Patient contraindications for blood collection
• Patients with a history of hypersensitivity to cimetidine or amino acid IV solution

Elders age more than 60 years who are non-frail and has no limited life expectancy